Electric furnace



Dec. 14 1926. 1,610,819

C. STEENSTRUP ELIEG'IIRIC FURNACE Filed Feb. 15. 1926 Inventor Christian Steensfrup XZ: T H15 Attorney.

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Patented Dec. 14; 1925.

UNITED STATES PATENT OFFICE.

CHRISTIAN STEENBTBUP, OF SCHENECTADY, NEW YORK, ASSIGNOB TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTBIOEURNACE.

Application filed February 15, 1926. Serial 1T0. 88,169.

The present invention relates to electrically heated furnaces of the type in which the operations are carried out in the presence of a; selected gas, such as hydrogen, for example.

In furnaces of this character especially those of large size, it is important to conserve both the heat and the selected gas fully as possible, so as to keep the operating costs of the furnace, both for electric current and gas as low as possible consistent with the work to be performed.

My invention has for its object to improve 7 the construction of electric furnaces of the character described to the end that the operating costs may be reduced to a minimum.

For a consideration of what I believe to be novel and my invention, attention is directed to the accompanying description and the claims appended thereto.

In the drawing which illustrates one of the embodiment. of my invention, Fig. 1 is a vertical section of an electric furnace; Fig. 2 is a partial horizontal section taken on line 22 of Fig. 1; Fig.- 3 is a detail view illustrating the means whereby selected portions of the charge may be inserted and withdrawn from the furnace; Fig. 4 is a view in elevation of the structure shown in Fig. 3, and Fig. 5 is a detail view of one of the labyrinth rings or strips.

. The furnace comprises three principalmembers-0r elements, a foundation 5, a rotatable base 6 and a container 7 which is closed except at its lower end. Both the base element and. the container'are heavily lined with heat-resisting material 8, such as fire brick, so as to conserve the heat within the heating chamber 9 as fully as possible. One or both of these membersis or are provided with resistors 10 through which the heating current flows, there being as usual flexible connections to a source of electric current supply. The base member is provided with a central pivot- 11 and the weight is sustained; by ball or roller bearings 12 which permitthe member to be easily, rotated. Additional' ball or roller bearings 13 are also provided which hold the member horizontal, facilitate turning thereof. and prevent cramping at thepivot. The base member or element supports the charge or work 14 which is undergoing treatment. The charge is made up of a number of individual pieces or port1ons which are inserted and withdrawn successively. the number of such pieces depending upon the length of time required to heat them to the desired temperature. The gen eral plan of operation after the furnace is in operation is to insert one cold piece or portion and withdraw one hot piece'or portion, such actions either taking place simultaneously or ingrelatively quick succession as will appear later.

The upper member or container is purpoiely made rather shallow so-as to make the heating chamber 9 as small as possible, having due regard for the shape and size of the portions of the charge. It may be raised and lowered by any suitable means. As shown it is moved by a rod 15 which is attached to a piston located within the cylinder 16. The piston may be operated by any suitable fluid, preferably by water under pressure subject to the control of a valve.

Selected gas, such as hydrogen for example, is admitted to the heating chamber by the pipe 17, some portion of which is flexible to permit of the up and down movements of the container. To prevent the escape of this gas, the pressure of which is slightly above atmosphere, a packing is pro- Vided between the container and base memher at the circumference thereof. It comprises a flat ring 18 which is carried by the base and a flat ring 19 which is carried .by the container. Both of these flat rings are provided with vertically disposed concentric rings 20, those on one plate being situated in the grooves or spaces between the rings on the other plate. These spaces are partially filled with a packing material 21 which may advantageously consist of small steel shot, such as are used in sand blasting. Sand is also another example of a packing material. It is desirable to sharpen the lower edges of the concentric packing rings of the container as shown in Fig. 5 so that the packing material may bemore .easily displaced when the container is lowered. In addition to preventing the escape of gas from the heating chamber it is also evident that the packing or sealing means also prevents the free escape of heat from within the furnace and through the joint between the members.

If the container were raised bodily from the base to expose the entire charge it would resultin a very large waste of heat on account of the large opening thus provided. It would also result in a greatly increased consumption of the selected gas for in a furnace of this character, it is necessary to maintain a body of gas within the heating chamber sufficient to prevent air from havmg access to the resistors and also to prevent the trapping of air within thechamber when the furnace is again closed. Where hydrogen 1S employed it combines with the air to form a burning mixture and with the furnace open enough gas must be supplied to keep the burning area at or about the level or point which is open to the air. Furthermore, it the charge is compo:ed of a number of relatively small pieces or portions they would all be exposed to the effects of air which it is important toprevent since the a1r would. cause more or less oxidation during the ex posed period.

References will now be made to the-means whereby the heat within the heating chamber 9 and the supply of selected gas arebotlL conserved during the periods that the successive portions of the charge are removed and introduced. At some point in their circumference, the packing rings 20 which move with the container are provided with registering openings 25 to form a charging opening or means as best shown in Figs. 3 and These openings are of such size as to permit portions of the charge to be inserted into and withdrawn from the heating chamber. To do this it is only necessary to raise the container by a slight amount, it being noted that at no other place in the circumference of the container is the sealbroken. With the parts as shown in Figs. 3 and 4: a tool such as a hook can be inserted through the opening to the farther edge of the portion of the charge to be removed and said portion pulled out through the opening. To protect the edges of the labyrinth packing carried by the base a properly curved plate 26 is placed over them and is subsequently removed. By preference the top surface of the plate is level with the top surface of'the base so as to offer no obstruction to movements of the charge. When the container is thus elevated the supply of gas through the inlet pipe 17 should be suflicient to cause the burning area to be located outside the innermost packing ring on the container so as to prevent air from entering the chamber which might form an explosive mixture and which would slightly oxidize the other portions of the charge. The charging opening in the packing rings is small, being only slightly larger in cross section than the portions of the charge and hence the additional amount of gas required to maintain the burning area at the proper place is insignificant. For the same reason, the amount of heat which can escape from the heating chamber is also very small, especially when contrasted with what it would be if the container were raised to a point where the entire seal were broken. While the container is in its slightly elevated position a new portion of the charge may be inserted if desired by a pushing action. is preferable, however, to do the loading at another point, say 90 from the unloading point, the reason being that the introduction of a body of cold metal would have a'tendency to slightly coolbe desirable to have a second cutaway portion. In other words, to have a loading statron at one point in the circumference and an unloading station at another. After the portion of the charge has been removed or inserted as the case may be the ,curved plate 26 is removed and the container lowered.

In order to prevent the packing material from lodging on the lower wall of the opening 25 when the container is raised, it is preferable to bevel or round said wall as indicated at 27 in Fig. 5. It is preferable to bevel the upper wall of the opening at 28 so as to cause it to act as a wedge on being lowered into the packing material. Beveling this wall also decreases the danger of the tool or charge catching when being inserted or withdrawn.

The furnace herein described is intended especially for uniting parts by the fusion of metal, as for example by the use of copper as a fusing metal, the operation within the furnace taking place in the presence of a selected gas but it is to be understood that it is applicable to other purposes, as for example, annealing.

In order thatthe charge may be inspected during the furnace'operation, one or more valved sight tubes 29 are provided and located at any suitable point or points.

As indicated, the base element and container are relatively rotatable and are also relatively movable in a vertical plane. To facilitate the relatively rotary movements one of the members, as for example, the base, is provided with an actuator 30.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but

.I desire to have it understood that the apparatus shown is only illustrative and that the invention maybe carried out by other means. What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a furnace of the character described, the combination of a container in which an atmosphere of non-oxidizing gas is maintained, heating means therefor, means for supporting a charge within the container, and means for withdrawing a portion of'the chargeand inserting a new portion without new portion without ex osin the other portion of the charge wit int e container to the effects of atmospheric air.

3. In a furnace of the character described, the combination of a 'container member which is closed except at one end and is adapted to contain a non-oxidizing gas, a

second member forming the closure for the first, a support on which one member may be rotated with respect to the other, and an annular packing means which prevents the free escape of gas from within the furnace, means for heating the interior of the furnace, and means whereby a portion of the charge undergoing treatment can be removed from the container member without exposing the remainder of the charge to the effects of air. I

4. In a furnace, the'combination of a container which is lined with heat-resisting material and is closed except at one end, a heating device within the container, a member which closes the open end of the container, the two forming a closed chamber, said member also supporting the charge, means for maintaining a non-oxidizing gaseous medium in the chamber, means for inserting and withdrawing a portion of the charge from the chamber without subjecting the other portion to the effects of atmospheric air, and means for moving the container and member relatively to each other to permit of inserting and removing the charge.

5. In a furnace, the combination of a pair of members which define between them a closed heating chamber, one of said members having a normally closed opening which when opened permits the introduction to and removal of a charge from the chamber, and means for maintaining within the chamber an atmosphere of non-oxidizing gas of sufficient pressure to cause the burning area of the gas to extend into said opening when the latter is exposed to permit manipulation of the charge.

6. In a furnace, the combination of two members which are relatively movable, a heating means therefor, a sealing means for the joint between the members having a normally closed opening through which a charge may be introduced and removed, and means for moving the members relatively to each other to expose said opening.

7. In a furnace, the combination of two members which are relatively movable in a vertical direction, a heating means therefor, a seal comprising elements associated with the members, one of said elements having a normally closed opening through which a charge may be introduced and removed, and

means for moving one member and its seal- 1 ing element with respect to the other member and its sealing element to expose said opening.

8. In a furnace, the combination of two members which are relatively movable in Vertical and horizontal planes, a heating means therefor, between the members which have a normally a labyrinth packing means closed opening through which a charge may be introduced and removed, and means for moving the members and packing means relatively to each other to expose said openin e In a furnace, the combination of a container, a base member, the two defining a heating chamber, a heating means for the chamber, packing means located at the circumference of the container and base and provided with a charging o ening, means for moving the base angular y, and means for moving the container and base relatively to each other in a vertical plane to expose said opening to permit the introduction and removal of the charge.

10. In a furnace, the combination of two 'members which are relatively movable, and

define a heating chamber, a heating means therefor, conduit means for supplying a selected gas to the chamber, a packing for the joint between the members which has a normally closed chargin opening, and means for moving the mem rs and parts of the packing so as to expose said opening and permit the insertion and withdrawal of a charge.

11. In a furnace, the combination of a chambered container which is lined with heat-resisting material and is closed except at one end, a heating device within the container, ,a member which closes the open end of the container, a seal between the container and member, and means for moving the container and member with respect to each other to open a portion only of the seal to permit the introduction or withdrawal of a charge.

12.'In a furnace, the combination of a chambered container which is lined with heat-resisting material, an electricresistor supported within the container, a member which completes the closure of the container, a seal between the container and member, means for moving the container and member with respect to each other by an amount sufiicient only to open a limited portion of the seal to permit the introduction or withdrawal of a charge, and means for maintaining a supply of chamber, and means for maintaining asupply of gas within the chamber of suiiicient pressure to prevent the admission of air during the manipulation of the charge.

14. In a furnace, the combination of a container, means for raising and lowering it,

a base member which closes the container, a device by which the base,is rotatably supported, a packing for the joint between the container and base member, a means through which a charge can be removed from or inserted into the container, after the container and base have" been moved to predetermined positions, and means to prevent the entrance of air to the container during charging operations.

15. In a furnace of the character described, the combination of a relatively large container which is lined with heat-resisting material, controllable conduit means for supplying a non-oxidizing gas to the con.-

removed from the chamber aftertainer .and maintaining thereina ressure above that of the atmosphere, e ectrical means within the container ca able of heating the same to a relatively igh temperature, means within the container arranged '7 to receive and support a number of individual pieces which collectively form the charge, and means defining a small opening through which the ieces forming the charge can be individual y removed without exposing the charge-containing chamber of the container and the other pieces therein to the effects of atmospheric air.

16. In a furnace of the character described, the combination of a relatively large container which is lined with heat-resisting material, controllable conduit means for sup plying anon-oxidizing gas to the container and maintaining therein a pressure above that of the atmosphere, electrical means within the container capable of heating the same to a relatively high temperature, means within the container arranged to receive and support a number of individual pieces which collectively form the charge,

and means defining small openings through which pieces forming the char 6 can be in 'dividually inserted and remove without exposing the charge-containing chamber of the container and the other pieces therein to the efiects of atmospheric air.

In witness whereof, I have hereunto set my hand this 13th day of February, 1926.

CHRISTIAN STEENSTRUP, 

